Exposure to chemical pesticides during pregnancy was linked to a two-thirds increased risk of having an autistic child.
Researchers found pregnant women who lived close to fields and farms where chemical pesticides were applied had a significantly higher chance of having a child with autism, a University of California - Davis Health System news release reported.
The researchers looked at associations in between pesticides such as organophosphates, pyrethroids and carbamates and instances of developmental delay and autism.
"This study validates the results of earlier research that has reported associations between having a child with autism and prenatal exposure to agricultural chemicals in California," lead study author Janie F. Shelton, a UC Davis graduate student who now consults with the United Nations, said in the news release. "While we still must investigate whether certain sub-groups are more vulnerable to exposures to these compounds than others, the message is very clear: Women who are pregnant should take special care to avoid contact with agricultural chemicals whenever possible."
In California, where the study was conducted, about 200 million pounds of active pesticides are applied every year. Pesticides are necessary for maintaining the $38 billion revenue business, but they come with a number of health concerns.
Researchers looked a study encompassing about 1,000 participants including families that had a child between the ages of two and five who had been diagnosed with autism. The majority of the participants lived in "Sacramento Valley, Central Valley and the greater San Francisco Bay Area," the news release reported.
The team identified 21 chemical compounds in the region that were in the organophosphate class; the second most popular type of pesticides was pyrethroids.
"We mapped where our study participants' lived during pregnancy and around the time of birth. In California, pesticide applicators must report what they're applying, where they're applying it, dates when the applications were made and how much was applied," principal investigator Irva Hertz-Picciotto, a MIND Institute researcher and professor and vice chair of the Department of Public Health Sciences at UC Davis, said in the news release. "What we saw were several classes of pesticides more commonly applied near residences of mothers whose children developed autism or had delayed cognitive or other skills."
The team found that during the study period about one-third of the participants lived within 1.25 to 1.75 kilometers of a commercial pesticide application site. Organophosphate exposure during pregnancy was linked to an increased risk of autism in offspring, a mild association was observed with pyrethroids; Carbamates were linked with developmental delay.
"In that early developmental gestational period, the brain is developing synapses, the spaces between neurons, where electrical impulses are turned into neurotransmitting chemicals that leap from one neuron to another to pass messages along. The formation of these junctions is really important and may well be where these pesticides are operating and affecting neurotransmission," Hertz-Picciotto said.
The researchers strongly suggest that mothers take prenatal vitamins to reduce the risk of having a child with autism. It's almost impossible to completely eliminate chemical exposures, but finding ways to reduce them can be beneficial.
"We need to open up a dialogue about how this can be done, at both a societal and individual level," Hertz-Picciotto said. "If it were my family, I wouldn't want to live close to where heavy pesticides are being applied."
